The present invention relates to a method enabling diagnoses to be performed simply, effectively and quickly of the condition of existing civil engineering works, such as conduits and galleries subjected over time to stresses which may cause either localized degradations (adversely affecting their use) or generalized disturbances which may range from the presence of wide-open cracks to complete destruction, in order to perform the making of a diagnosis of the condition of the said structures by establishing a law on overall properties to ensure the reliable and efficient inspection and/or servicing and/or repair; it also relates to equipment enabling the said method to be implemented.
It is well known that civil engineering works, such as conduits or galleries allowing, for example, the supply of drinking water or any other consumer product, the disposal of effluent, road or railway tunnels . . . , are based on materials which age with time as a result of the physicochemical attacks centered on them, of the modifications of the conditions of use and of any changes in the features of the surrounding ground, and that the stresses to which they are subjected may give rise to more or less substantial localized degradations which therefore require not only inspection but also servicing and reconditioning.
To date, the maintenance and servicing of such structures is based on a method which, in a general manner, consists of visual observation and non-destructive auscultations enabling the quality or homogeneity of the lining or of the surrounding soil to be assessed. In order to perform such non-destructive auscultations, methods are used making use of ultrasonics, radar, acoustics, gamma radiometry. . . These methods, however, have the disadvantage of being unable to draw a reliable conclusion about the safety offered by the structure. Consequently, they are completed by destructive tests which consist, in a general manner, in taking samples and subsequent laboratory analysis.
None of the methods proposed to date, however, are entirely satisfactory since they take a long time and are awkward to implement, in particular when underground conduits are concerned.